CN117044078A

CN117044078A - Electric motor with bayonet coupling between stator and busbar unit

Info

Publication number: CN117044078A
Application number: CN202280023173.8A
Authority: CN
Inventors: J·施密德; T·库伯勒
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 2021-02-11
Filing date: 2022-02-04
Publication date: 2023-11-10
Also published as: WO2022172138A1; DE102021103295A1

Abstract

The invention relates to an electric motor having a rotor and a stator (2) surrounding the rotor from the outside, the stator having a wound coil, wherein the winding is formed by at least one winding wire with a winding wire end portion, and the winding wire end portion is in electrical contact with a bus bar in a bus bar unit (1) on the end side, wherein the bus bar unit (1) is arranged on the upper side of the stator (2), and wherein the stator (2) and the bus bar unit (1) are directly connected to each other by means of a bayonet joint (10).

Description

Electric motor with bayonet coupling between stator and busbar unit

The invention relates to an electric motor according to the preamble of claim 1.

The electric motor (which is referred to as an inner rotor) has a rotor that is connected to the motor shaft and is rotatably supported in a housing. The rotor is provided with permanent magnets. A stator is arranged around the motor, the stator carrying a plurality of windings on a core. Under proper control, the windings generate a magnetic field that drives the rotor to rotate. The windings are typically three-phase wound and are therefore provided with three electrical connections through which the windings can be connected to a control unit (ECU). The winding heads are connected by bus bars or bus bars. Generally, two bearing systems may be provided for securing the rotor. These bearings are typically implemented as ball bearings with an electromagnetic assembly located between the bearings. For motors with high noise requirements, the bearings are preloaded with spring elements. Thereby, the bearing end cap accommodating the bearing is applied with an axial force. Thus, both bearing end caps must be connected to the motor housing so that the interface can absorb the axial forces generated.

The multipolar brushless motor includes a stator with coils that are electrically connected. For mass-produced motors, this is usually achieved by means of a busbar unit. The busbar unit (which is composed of the busbar holding means and the busbars arranged therein) is mechanically connected to the stator. It is known that the busbar unit forms a connection with one of the bearing end caps. The mechanical connection must therefore be able to absorb axial forces.

The object of the invention is to provide an electric motor having a simple and axial force-absorbing connection between the busbar unit and the stator.

This object is achieved by an electric motor having the features of claim 1.

For the geometric description of an electric motor, in particular a multi-pole brushless motor, it is first assumed that the rotational axis of the motor is the central axis and the symmetry axis. A stator is arranged concentric with the rotation shaft and the rotor. The rotation shaft defines at the same time an axial direction in which the thickness of the stator group and the axial length of the motor are given. Furthermore, with respect to the central axis, radial directions, which represent distances from the central axis, and circumferential directions, which represent tangential directions of a specific diameter arranged in the radial directions, are also mentioned. The joint side of the stator (on which the windings are connected to the busbar arrangement) is described as the upper side of the stator.

An electric motor is proposed, which has: a rotor; and a stator surrounding the rotor from the outside, the stator having a wound coil. The winding is formed of at least one winding wire with a winding wire end portion, and the winding wire end portion is in electrical contact with a bus bar in a bus bar unit at an end side, wherein the bus bar unit is arranged at an upper side of the stator. A simple and safe connection between the stator 6 and the busbar unit is produced by means of the bayonet fitting. The bayonet fitting absorbs axial forces well and is also easy to install, thus requiring neither high installation forces nor additional components.

In a preferred embodiment, the stator comprises insulators, each of which comprises a winding chamber with a winding space, wherein the winding space is surrounded on the inside by an inner flange and on the outside by an outer flange, wherein the windings of the coil are formed around the insulators in the winding space, and wherein the insulators have protrusions which are insertable into corresponding grooves on the underside of the busbar unit in order to form bayonet joints. The manufacture of this embodiment is particularly simple and low cost, since interlocking parts can be formed during the manufacture of the insulator and busbar unit. Preferably, the two parts are formed by means of injection moulding.

Advantageously, each projection is formed at the outer side of the outer flange with the end side facing upward, wherein the busbar unit has a centrally located, through opening, and the recess is formed at the inner side of the busbar unit with the end side facing downward.

Preferably, the protrusions have hooks that are engaged in side recesses of the grooves, respectively, so as to form connection of the stator with the bus bar unit in the axial direction.

Preferably, the bayonet fittings are secured by locating rails formed in the busbar unit. Advantageously, when the stator has a stator core set, it has radially outwardly open grooves on the outside, which grooves are evenly spaced apart in the circumferential direction and extend in the longitudinal direction, wherein, for fixing the bayonet fitting, the positioning rail engages into one of the grooves on the end side.

It is also advantageous if the insulator is connected to a stator-core set of the stator by means of a coil, wherein the stator is in turn fixed in the motor housing of the motor by means of an interface between the stator-core set and the inner wall of the motor housing. Thereby being able to safely absorb the force introduced into the bearing end cap located above the bus bar unit.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Components of the same type or function are denoted by the same reference numerals in the figures. Shown in the drawings are:

fig. 1: a longitudinal section through the busbar unit and a part of the stator;

fig. 2: the detail view of fig. 1;

fig. 3: the spatial view of the components connected to each other of fig. 1;

fig. 4: a spatial view of the busbar unit and the entire stator; and

fig. 5: fig. 4 is a detailed view.

Fig. 1 shows a sectional view of a busbar unit 1, which busbar unit 1 is located above a stator 2 of an electric motor. The busbar unit 1 generally comprises a busbar holder 3 and a busbar, not shown, arranged in the busbar holder 3. The bus bars are made of an electrically conductive material, preferably metal, in particular copper. The bus bar holding device 3 is at least partially or completely made of an electrically insulating material, so that short circuits between the bus bars can be effectively avoided. The busbar holder 3 is preferably produced by injection molding. The bus bar holding device 3 is in contact on the axial side (upper side) of the stator 2 and is connected thereto. Only the insulator 4 of the stator is shown in fig. 1. The insulators 4 each enclose a stator tooth, not shown, and isolate the stator tooth from the windings of the coil. The insulators 4 each have a winding space 5 for receiving a winding wire, which forms a winding space which is surrounded on the inside by an inner flange 6 and on the outside by an outer flange 7 in the radial direction relative to the longitudinal axis of the stator. The insulator 4 is connected to a stator-core group of a stator, not shown, through a coil group. The stator 2 is in turn fixed in the motor housing by means of a joint between the stator core set and the inner wall of the motor housing.

The winding ends, not shown, of the windings arranged in the stator 2 are electrically connected to the bus bars in a known manner. The busbar unit 1 is configured to be in electrical contact with the coil of the stator by means of a busbar. Each bus bar has a power connector element 8 configured to be electrically connected to a power source. The coils are grouped into three phase groups. Therefore, three power connector elements 8 are provided in total, which extend from the upper side of the busbar unit 1 (as shown in fig. 1 and 3), and form a connector 9 for electrical connection to a control unit, not shown.

The insulator 4 is directly connected with the busbar unit 1 by means of the bayonet fitting 10.

As shown in fig. 1 to 3, the outer flange of the insulator 7 has an end-side, upwardly facing projection 11 at the outer side, which projection 11 engages into a corresponding recess 12 on the inner side of the busbar unit 1 and thereby forms a bayonet fitting 10. The projection 11 is hook-shaped, in particular L-shaped, and is inserted into the bus bar holding device 1 from below upward in the axial direction. The busbar unit 1 has a substantially circular through opening 13 in the lower part, which forms a circumferential edge 14 in the lower region. At the time of installation, the stator 2 and the insulator 4 are inserted into the opening 13 from below. The recess 12 is provided inside the rim 14. The recess 12 is formed such that the stator 2 and the insulator 4 can be inserted so as to be rotated by an angle in the circumferential direction of the relative axial direction with respect to the busbar unit 1 so that the hook 11 engages into the undercut 15 of the recess 12 and forms a fixed connection of the two components 1, 2 that can be loaded in the axial direction. The assemblies 1, 2 can be separated from each other again by rotation in opposite directions.

Fig. 4 shows a stator 2 with a stator core group 16 and a busbar unit 1 connected directly above the stator 2 by means of a bayonet fitting 10. The stator core group 16 has radially outwardly opening grooves 17 on the outside, which grooves 17 extend parallel to the longitudinal axis and are evenly spaced apart in the circumferential direction. A positioning ledge 18 is formed at the underside of the busbar unit 1, which positioning ledge 18 engages or snaps into one of the grooves 17 in the stator core set from above and serves as a safety against the release of the bayonet fitting 10 once the bayonet fitting is axially connected to the stator by rotating the busbar unit.

The engagement in the grooves of the stator core groups 17 is shown in detail in fig. 5. The positioning rail 18 is first tensioned in the axial direction when rotating the components 1, 2 to be connected relative to each other. Once the groove 17 is reached upon rotation, the positioning rail 18 snaps axially downwards into said groove 17 and forms a safety device preventing the bayonet joint from opening.

Claims

1. An electric motor with a rotor and a stator (2) surrounding the rotor from the outside, the stator (2) having a wound coil, wherein the winding is formed by at least one winding wire with a winding wire end portion, and the winding wire end portion is in electrical contact with a bus bar in a bus bar unit (1) at the end side, wherein the bus bar unit (1) is arranged on the upper side of the stator (2), characterized in that the stator (2) and the bus bar unit (1) are directly connected to each other by means of a bayonet joint (10).

2. The electric motor according to claim 1, characterized in that the stator (1) comprises insulators (4), each insulator (4) having a winding chamber (5) with a winding space, wherein the winding space is surrounded on the inside by an inner flange (6) and on the outside by an outer flange (7), wherein the windings of the coil are formed in the winding space around the insulators (4), and wherein the insulators have protrusions (11) which can be inserted into corresponding grooves (12) on the underside of the busbar unit (1) in order to form the bayonet joint (10).

3. The electric motor according to claim 2, characterized in that each of the protrusions (11) is formed at the outer side of the outer flange (7) with the end side facing upward, wherein the busbar unit (1) has a centrally located, through opening (13), and the groove (12) is formed on the inner side of the busbar unit (1) with the end side facing downward.

4. A motor according to claim 2 or 3, characterized in that the protrusions (11) have hooks, each of which engages in a undercut (15) of the groove (12) to form a connection of the stator (2) with the busbar unit (1) in the axial direction.

5. The electric motor according to any of the preceding claims, characterized in that the bayonet fitting (10) is fixed by means of a positioning rail (18) formed in the busbar unit (1).

6. The electric motor according to claim 5, characterized in that the stator (2) has a stator core group (16), which stator core group (16) has radially outwardly open grooves (17) on the outside, which grooves (17) are evenly spaced apart in the circumferential direction and extend in the longitudinal direction, wherein, for fixing the bayonet fitting (10), the positioning rail (18) engages into one of the grooves (17) on the end side.

7. The electric motor according to any of the preceding claims, characterized in that the insulator (4) is connected to the stator-stator core set (16) of the stator by means of the coil, wherein the stator (2) is in turn fixed in the motor housing of the electric motor by means of an interface between the stator-stator core set (16) and the inner wall of the motor housing.